net/mlx5e: use indirect calls wrapper for skb allocation

We can avoid an indirect call per packet wrapping the skb creation
with the appropriate helper.

Signed-off-by: Paolo Abeni <pabeni@redhat.com>
Acked-by: Saeed Mahameed <saeedm@mellanox.com>
Signed-off-by: David S. Miller <davem@davemloft.net>